I remember that era pretty fondly and I don't ever recall just typing in random URLs, except maybe jokey ones like sex.com or fuck.com for kicks. We had Yahoo's search engine at the time and worked well enough. And to a lesser extent Lycos/Hotbot/Inktomi/DMOZ. The pre-Google web was pretty interesting and a bit more sophisticated than gets credit today. I also feel you were less likely to discover retailers on the web randomly. You'd more than likely hear about them first on the news or from friends and go from there. I don't think it was common to just discover some random e-tailer like we do today, put in our credit card, and expect the package in a couple days. You learned about Amazon from 60 minutes or your friend who subscribed to Wired magazine or the guy at the software store, not from a search engine.

I think the whole pets.com and travel.com is just the usual marketing logic at work and not really related to the limitation of search engines. Its just shady marketing tricks, a bit like how we see the .biz and other gimmicky tlds today.